Compressor valve control mechanism



Dec. 12, 1950 w, AiEATON 2,533,777

COMPRESSOR VALVE CONTROL MECHANISM Filed Sept. 6, 1944' IN VEN TOR.

A TIP/ENE Yj Patented Dec. 12, 1950 COMPRESSOR VALVE CONTROL MECHANISM Wilfred A. Eaton, Elyria, Ohio, assignor to Bendix-Westinghouse Automotive Air Brake Company, Elyria, Ohio, a corporation of Delaware Application September 6, 1944, Serial N 0. 552,924

5 Claims.

This invention relates to control mechanism, and more particularl to mechanism for controlling the flow of fluid pressure supplied by a pump or compressor.

It has previously been customary in connection with pumps and compressors, and particularly in connection with pumps for compressing air, to provide means controlled by the pressure in the reservoir for automatically controlling the compressor to prevent the further pumping of fluid pressure when the pressure in the reservoir reaches a predetermined value. Various mechanisms have been utilized for accomplishing this desirable end, but many of these mechanisms have been complicated and costly, and it is accordingly one of the objects of the present invention to provide unloading mechanism of a relatively simple and inexpensive nature for controlling such a pump or compressor.

In controlling the operation of the compressor in the above referred to manner, it has been found essential to provide a so-called snap action of some sort which would act to definitely unload the compressor when a predetermined pressure was reached in the compressor reservoir, and to load the compressor when the pressure in the reservoir was decreased by a predetermined value, in some cases this has required the use of a fluid pressure actuator for operating unloader valves in the compressor, together with a separate governor controlled by variations of pressure in the reservoir for supplying fluid pressure to the actuator when the pressure in the reservoir exceeded a predetermined value, and it is accordingly another object of the invention to provide unloading mechanism so constituted as to eliminate the need for a separate governor of the snap action type to control the supply of fluid pressure to an unloader valve actuator.

Yet another object of the invention is to provide novel unloading valve actuator means operated directly by reservoir pressure for operating the unloader valves.

A still further object of the invention is to provide novel snap action means for insuring immediate and positive opening of the unloading valves when a predetermined pressure is reached in the reservoir, and for insuring immediate and positive closing of the valves when the pressure in the reservoir changes by a predetermined value.

A further object of the invention is to provide magnetic means for insuring instantaneous and positive operation of the unloading valves when the pressure in the reservoir exceeds or becomes less thana predetermined value.

Yet a still further object of the invention is to provide means for adjusting the unloader mechanism in order to vary the pressures at which the compressor is loaded and unloaded.

These and other objects of the invention will be more readily apparent :when taken in connection with the accompanying drawing, wherein one form of the invention is illustrated. It is to be expressly understood, however, that the drawing is employed for purposes of illustration only, and is not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawing, the single view is a diagrammatic representation, partially in section, of a compressor and fluid pressure supply system having unloader mechanism constructed in accordance with the principles of the present invention.

In the drawing, a fluid pressure system is illustrated as including generally a compressor 4, a supply reservoir 5 adapted to receive fluid pressure from the compressor through conduits t5 and 6a, and an unloading mechanism preferably mounted integrally with the compressor. The

.' compressor is provided with a cylinder 8 having a piston 9 slidably mounted therein and driven by a crankshaft :0 connected thereto by means of a connecting rod H of conventional type. The upper end of the cylinder 8 is provided with a cylinder head l2 having a discharge cavity it formed therein and connected to the lower end of the conduit 6a. The cavity i3 is connected with the portion of the cylinder aaove $138 piston by means of a discharge port It! formed in the cylinder, and the flow of fluid pressure from the cylinder to the discharge cavity is normall prevented by means of a discharge valve l5 maintained against the upper end of the port by means of a spring l6, and it will be understood that as the piston moves upward in the cylinder, fluid pressure will be forced into the cavity through the'port and past the discharge Valve. The left wall of the cylinder is provided with an inlet port I1, and the left end of this port is provided with a valve seat member it having a bore Hi therethrough. The right end of the bore is provided with a valve seat, and an inlet valve 20 of the disc type is normally maintained against the seat by means of a relatively light spring 2! interposed between the right side of the valve disc and a flange formed on the right end of a tubular valve guide member 23 positioned in a portion of the inlet port [1 by fluted guides 23a formed thereon, the central portion of the member 23 being provided with a port 24 in register with provided with a cover member 26a.

the inlet port in the cylinder wall. The left end of the member 23 is spaced from the right end of the valve seat member I8, and thus fluid pressure is free to pass therebetween from the inlet valve and past the fluted guides 23a into the cylinder through inlet port ll. Thus on downward movement of the compressor piston, the port ll is uncovered by the upper end of the piston and fluid pressure is drawn into the compressor cylinder through the port [9, the inlet valve 20, past guides 23a and through inlet port It has previously been proposed to unload a compressor or pump by providing mechanism for maintaining the inlet valve open when the pressure in the reservoir exceeds a predetermined value, and in the present invention, relatively simple means have been provided for effecting this desirable result. To this end, an unloader casing 25 is attached to the compressor cylinder by means of bolts 26 as shown, this casing being A flexible diaphragm 21 is clamped between the cover and the housing in order to define a diaphragm chamber 28 which is connected with the reservoir by means of a conduit 29, it thus being apparent that the diaphragm is subjected at all times to the pressure in the reservoir. A diaphragm follower 30, preferably in the form of a disc, is loosely mounted in the cover at the left of the diaphragm, and is adapted on movement ofthe diaphragm to the left to engage a projection 3! formed on an unloading lever 32 pivotally mounted on the cover by means of a pivot pin 33. The right end of the lever is provided with an adjusting screw 35 and a lock nut 35, and on clockwise rotation of the lever, the inlet valve is moved to open position by means of a plunger 36 slidably mounted in a bore 3'! formed in the casing, the left end of the plunger being maintained in engagement with the right end of the adjusting screw 34 by means of a spring 38 interposed between a flange 39 formed on the plunger and aportion of the casing, and the right end of the plunger being normally spaced slightly from the left surface of the inlet valve disc. Thus under normal operating conditions, the inlet valve is free to operate without interference from the plunger, and as the pressure in the reservoir and in the diaphragm chamber 28 increases, as will be more fully explained hereafter, the lever will be rotated in a clockwise direction to move the inlet valve to open position and maintain the valve in that position until the pressure in the reservoir decreases by a predetermined value.

In order to insure this type of operation, the lever is biased in a counterclockwise direction by means of a spring 49 interposed between the lower end of the lever and an adjusting screw 4| supported by an arm 2 formed on the cover 26, and the arm, which in the embodiment shown is made of a magnetic material such as iron, is

' further normally maintained in the position shown by means of a permanent magnet 43 suitably secured to'the cover by means of bolts 44.

' netic force will substantially. disappear as soon asthe lever starts to rotate in a clockwise direction, the additional fluid pressure force which has been built up to overcome the magnet force will be sufficient to rapidly move the inlet valve on the compressor to open position through the connections heretofore described. As the lever rotates in the above direction, this motion is limited by means of a second permanent magnet 45, attached to the arm 32 by'means of bolts 46, and since the lever is made of magnetic material, the left surface of the lever will abut and will adhere to the poles of the magnet 45. Thus the lever will be maintained in unloading position by the force exerted by the diaphragm as well as by the force exerted by the permanent magnet 45, while the spring 40, which has been compressed during the above motion of the lever, will tend to move the lever back to its original position. As the pressure in the reservoir 5 and the diaphragm chamber 28 decreases, the lever'will continue to adhere to the poles of the magnet 45 until the pressure in the diaphragm chamber drops sufiiciently to permit the force exerted by the spring 48 to move the lever back to the position shown on the drawing, whereupon the plunger 36 will be moved to the left by theoperation of the spring 38, and the inlet valve will be permitted to move to closed position under the action of the inlet valve spring 2|, thus'permitting the inlet Valve and the compressor to function in the normal manner to supply fluid pressure to the reservoir. j

It will be understood from the foregoing that the tension of the spring may be adjusted by the adjusting screw 4| to determine, dependent on the design'of the permanent magnet 43, the pressure at which the lever is rotated in a clockwise direction in order to open the inlet valve of the compressor, While the design of the permanent magnet 45 may be so chosen with respect to the design of spring 4 0 as to definitely determine the drop in pressure necessary to effect reverse movement of the unloader arm underthe action of the spring. In View of the inclusion of the permanent magnets 43 and 45 in the system utilized for controlling the operation of the unloader arm, a definite snap action is obtained during operation of the arm in either direction which'insures instantaneous and positive opening and closing of the compressor inlet valve or unloader valve in response to prededetermined variations of pressure in the supply reservoir. While the magnets are shown as being permanently positioned with respect to the unloader arm, itwill be understood that adjustment of the positions of these magnets may be effected to change the pressure range of the mechanism by the removal or'additionof shims r ent invention is shown as operating an inlet valve of the automatic type positioned in the wall of the compressor cylinder, and therefore a more easily moved to open position in view of the fact that it is never subjected to the full pressure developed by thecompressor, itwill be further understood by'those skilled in the art that the inlet valve'orvalves may be located in' the cylinder-head of the compressor or elsewhere, or that separate unloader'valves or other control means may be utilizedand operatedin the same manner by the movement of the unloader arm 32 in order to unload and load the compressor. As shown in the drawing, the inlet valve is located in the side wall of the cylinder and hence partial unloading of the compressor is secured when the valve is maintained in open position through operation of the unloader. However, with the inlet valve positioned in the cylinder head, as above indicated, it will be understood that substantially complete unloading of the compressor may be achieved. Thus, it is apparent that the desired degree of unloading may be readily obtained by varying the location of the inlet valve with respect to the stroke of the piston.

Although the invention has been illustrated and described herein with considerable particularity, it is to be understood that the same is not limited to the form shown, [but may receive a variety of mechanical expressions, as will readily appear to those skilled in the art. Reference will, therefore, be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. In combination, a compressor having a cylinder, a discharge chamber connected to said cylinder for receiving fluid pressure from the cylinder, an inlet port in the cylinder wall of the compressor, and a valve for normally closing said port, unloader mechanism for said compressor including a plunger operable to move said valve to open position, means for normally maintaining said plunger out of engagement with said valve, a lever for operating said plunger, means subjected at all times to the pressure in said discharge chamber for moving the lever and plunger in valve opening direction, a spring for moving the lever in the opposite direction, means for adjusting the tension ofsaid spring, and means for preventing movement of said lever in said valve opening direction or in said opposite direction except in response to predetermined variations in pressure in said discharge chamber including a permanent magnet normally in engagement with the lever for opposing movement of the latter in said valve opening direction with a predetermined force and a permanent magnet engageable by the lever on a predetermined degree of movement thereof in said valve opening direction for opposing movement of the lever in said opposite direction with a predetermined force.

2. In combination, a compressor having a cylinder, a discharge chamber for receiving fluid pressure from the cylinder, an inlet port in the cylinder wall of the compressor, and a valve for normally closing said port, unloader mechanism for said compressor including a plunger operable to move said valve to open position, means for normally maintaining said plunger disengaged from said valve, means for adjusting the degree of said disengagement, a lever for operating said plunger, means subjected at all times to the pressure in said discharge chamber for moving the lever and plunger in valve opening direction, a spring for moving said lever in the opposite direction, means for adjusting the tension of said spring, and means for preventing movement of said lever in said valve opening direction or in said opposite direction except in response to predetermined variations of pressure in said chamber including a permanent magnet normally in engagement with the lever for opposing movement of the latter in valve opening direction with a predetermined force and a permanent magnet 6 engageable by the lever on a predetermined degree of movement thereof in valve opening direction for opposing movement of the lever in said opposite direction with a predetermined force.

3. In combination, a compressor having a cylinder, a discharge chamber connected to said cylinder for receiving fluid pressure from the cylinder, an inlet port in the cylinder Wall of the compressor, and a valve for normally closing said port, unloader mechanism for said compressor including a plunger operable to move said valve to open position, means for normally maintaining said plunger out of engagement with said valve, a lever for operating said plunger, means subjected at all times to the pressure in said discharge chamber for moving the lever and plunger in valve opening direction, a spring for moving the lever in the opposite direction, means for adjusting the tension of said spring, means for preventing movement of said lever in said valve opening direction or in said opposite direction eX- cept in response to predetermined variations of pressure in said chamber including a permanent magnet normally in engagement with the lever for opposing movement of the latter in valve opening direction with a predetermined force and a permanent magnet engageable by the lever on a predetermined movement thereof in valve opening direction for opposing movement of the lever in said opposite direction with a predetermined force, and means for adjustably positioning said magnet with respect to said lever.

4. In combination with a pump and a reservoir connected thereto, said pump having a valve operable to prevent or permit the pumping of fluid by the pump to the reservoir, unloader mechanism for the pump including an element for controlling the operation of said valve, means responsive at all times to the pressure in the reservoir for moving the element in one direction, resilient means for moving the element in the other direction, means for adjusting said resilient means to vary the force exerted thereby, a permanent magnet engageable by the element and operative to oppose movement of the element in said one direction with a predetermined force, and a permanent magnet engageable by the element upon movement thereof in said one direction and operative to oppose movement thereof in said other direction with a predetermined force.

5. The combination with a reservoir and a compressor for supplying fluid pressure thereto having a connection therewith and having controlling means operable for permitting or preventing the supplying of fluid pressure to the reservoir by the compressor, of means for controlling the operation of said first named means in accordance with variations of pressure in said reservoir including a movable pressure responsive member subjected at all times to the pressure in said reservoir and having an operative connection with the first named means, and resilient means for opposing the movement of said member and operative connection, and means including a pair of permanent magnets for opposing movement of the pressure responsive member and operative connection in one direction in response to the action of fluid pressure thereon with a predetermined force and for opposing movement of the operative connection in the opposite direction by the action of said resilient means with a predetermined force.

WILFRED A. EATON.

(References on following page) REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Iversen Dec. 29, 1914 Colgate Apr. 11, 1922 Fisher Nov. 9, 1926 Christensen Apr. 26, 1927 10 Number Name Date 7 Farmer Apr. 23, 1929 Ochel Mar. 12, 1935 Ploeger June 2, 1936 Horlacher Nov. 24, 1936 1 Aikman Apr. 12, 1938 Anderson July 19, 1938 Dick Mar. 11, 1941 Bixler Jan. 4, 1944 

